JP2010226330A - Electromagnetic transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an electromagnetic transducer capable of acquiring a necessary drive force by receiving magnetic flux of permanent magnets even if the permanent magnets are inexpensive, and having a diaphragm of improved rigidity. <P>SOLUTION: The electromagnetic transducer includes: strip-like permanent magnets 10 disposed so as to have a predetermined gap 11 and have alternately different polarities; a diaphragm 20 in which protrusion bends 21a are formed along the predetermined direction of a base material, coils 22 are formed on the surface of the protrusion bends 21a and the protrusion bends 21a are disposed on the gap 11 having different polarities of the permanent magnet 10; and a frame 30 for housing the permanent magnets 10 and supporting the diaphragm 20. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electromagnetic transducer that reproduces an audio signal by combining, for example, a permanent magnet and a diaphragm.

Regarding an electromagnetic transducer in which a permanent magnet and a vibration membrane are combined, for example, according to Patent Document 1, a permanent magnet plate, a vibration membrane disposed so as to face the permanent magnet plate, and these permanent magnet plate and vibration membrane And a cushioning member disposed between the two.
The permanent magnet plate has a multi-pole magnetized pattern in which different belt-shaped magnetic poles are alternately formed at regular intervals, and the vibration film is a gap portion between different magnetic poles of the permanent magnet plate. A coil made of a meandering conductor pattern is formed on the entire surface at a position opposite to a so-called magnetized neutral zone.

  As a result, when a current (audio signal) flows through the coil of the diaphragm, the coil and the multipolar magnetized pattern of the permanent magnet plate are electromagnetically coupled, and audio vibration is generated in the diaphragm according to Fleming's law.

  The permanent magnet plate, the diaphragm and the buffer member are covered with a metal frame and attached to the speaker housing. Sound waves generated by the audio vibration are radiated through radiation holes provided in the permanent magnet plate and the metal frame. Audio playback.

  Such an electromagnetic transducer is inefficient because a magnet is disposed so as to sandwich the vibration film and a leakage flux of the magnet is used. Therefore, a magnet having a large maximum energy product (BHmax) such as a neodymium iron boron magnet is used to increase the magnetic flux density necessary for driving the diaphragm to obtain a sufficient sound pressure.

Japanese Patent No. 3192372 (JP 9-331596 A)

  However, the above-described conventional electromagnetic transducer has a problem that the efficiency is poor because the driving force of the vibrating membrane is obtained by the leakage flux of the permanent magnet. Further, since an expensive permanent magnet such as a neodymium iron boron magnet is used in order to obtain a large driving force, there is a problem that an electromagnetic transducer constituted by a magnetic circuit using this permanent magnet is expensive. Further, since the diaphragm is thin and has low rigidity, there is a problem that sound pressure level loss occurs due to split resonance.

  The present invention has been made to solve the above-described problems, and can efficiently receive the magnetic flux of the permanent magnet, obtain a necessary driving force even with an inexpensive permanent magnet, and improve the rigidity of the diaphragm. The purpose is to obtain an electromagnetic transducer.

  In the electromagnetic transducer according to the present invention, a strip-shaped permanent magnet disposed so as to have a predetermined gap and alternately different polarities, and a convex bent portion are formed along a predetermined direction of the substrate. A vibration film in which a coil is formed on the surface of the convex bent portion, and the convex bent portion is disposed in a gap between different polarities of the permanent magnet, and a frame that houses the permanent magnet and supports the vibration membrane It is a thing.

According to the electromagnetic transducer according to the present invention, the convex bent portion formed along the predetermined direction of the base material of the vibration film and having the coil formed on the surface thereof is disposed in the gap between the permanent magnets. By comprising, a coil can receive a big magnetic flux density from a permanent magnet, and even if it is an inexpensive permanent magnet, a required magnetic flux density can be obtained.
In addition, since the protrusion is formed by bending the vibration film, the sectional modulus of the vibration film is increased, the rigidity of the vibration film is improved, and the loss of the sound pressure level can be suppressed.

It is a figure which shows the whole structure of the electromagnetic transducer of this invention, (a) It is an exploded perspective view, (b) It is a side view. 2 is a cross-sectional view taken along line AA showing the configuration of the electromagnetic transducer according to Embodiment 1. FIG. It is an AA line sectional view showing other composition of an electromagnetic transducer concerning Embodiment 1. FIG. It is an AA line sectional view showing other composition of an electromagnetic transducer concerning Embodiment 1. FIG. It is an AA line sectional view showing other composition of an electromagnetic transducer concerning Embodiment 1. FIG. It is an AA line sectional view showing the composition of the electromagnetic transducer concerning Embodiment 2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram for illustrating the overall configuration of an electromagnetic transducer according to the present invention. FIG. 1 (a) is an exploded perspective view of the electromagnetic transducer, and FIG. 1 (b) is a side view of the electromagnetic transducer. .
2 is a cross-sectional view taken along the line AA of FIG. 1 showing the configuration of the electromagnetic transducer according to the first embodiment.

The structure of the electromagnetic transducer 1 of Embodiment 1 is demonstrated.
As shown in FIGS. 1A and 1B, the electromagnetic transducer 1 is roughly composed of a permanent magnet 10, a vibration film 20, and a frame 30, and the permanent magnet 10 is located between the vibration film 20 and the frame 30. It is accommodated and comprised so that it may be pinched | interposed into.

  The permanent magnet 10 is a strip-shaped magnet having a rectangular cross section, and is arranged so that the polarities are alternately different. The permanent magnet 10 has a predetermined gap as a magnetic air gap (hereinafter referred to as a gap) 11 as shown in FIG.

  The vibration film 20 is formed of a rectangular sheet having, for example, a thin and flexible resin film as a base material and a coil 22 formed on the surface thereof. In the longitudinal direction of the vibration film 20, a bent portion 21a is formed so that the surface facing the permanent magnet 10 is convex, and the cross section of the bent portion 21a is V-shaped. A coil 22 is formed on the surface of the bent portion 21a. The coil 22 is formed by, for example, a printing method similar to FPC (Flexible printed circuits), a method of winding a thin wire conductor, or the like.

The V-shaped bent portion 21 a formed on the vibration film 20 is disposed in the gap 11 between the permanent magnets 10, and the strong magnetic flux generated between the permanent magnets 10 by the coil 22 formed on the bent portion 21 a. Is in a position to receive.
Further, in order to fix the vibration film 20 to the frame 30 without disturbing the vibration of the vibration film 20, an edge 23 having a semicircular cross section is formed along the outer periphery of the vibration film 20.

  The frame 30 has a substantially rectangular parallelepiped shape, and one surface thereof is covered with the vibration film 20. A permanent magnet 10 is bonded and fixed to the inner surface facing the vibration film 20, and sound emitting holes 31 are formed at positions corresponding to the intervals between the permanent magnets 10.

Next, the operation of the electromagnetic transducer 1 will be described.
When a current as an audio signal is supplied from a control unit (not shown) to the coil 22 of the bending portion 21a of the vibrating membrane 20, the current flowing through the coil 22 and the magnetic flux generated in the gap 11 between the permanent magnets 10 are electromagnetically coupled. Then, according to Fleming's law, the diaphragm 20 is driven back and forth (up and down in FIG. 2) to generate audio vibrations. The generated audio vibration is emitted to the outside of the electromagnetic transducer 1 through the sound emission hole 31 of the frame 30.

  At this time, when a flat plate-like vibrating membrane is used, split resonance occurs and the sound pressure level is lost. However, the vibrating membrane 20 has a thin and flexible sheet-like cross section due to the formation of the convex bent portion 21a. Since the rigidity is improved by increasing the coefficient, the division resonance is braked and the loss of the sound pressure level is suppressed.

As described above, in the electromagnetic transducer 1 according to the first embodiment, the bent portion 21a in which the convex bending portion 21a is formed along the predetermined direction of the vibration film 20 and the coil 22 is formed on the surface thereof is used as the permanent magnet 10. With the configuration in which the coil 22 is arranged in the gap 11 therebetween, the coil 22 can receive the magnetic flux at the portion where the magnetic flux density between the permanent magnets 10 is high. As a result, even if an inexpensive ferrite magnet is used, the required magnetic flux density can be obtained, and even an expensive magnet such as a neodymium iron boron magnet can obtain the required magnetic flux density at a low cost by reducing the magnet volume. it can.
Further, since the bending portion 21a is formed, the section modulus of the diaphragm 20 can be increased and the rigidity can be improved. Therefore, the division resonance of the thin diaphragm 20 can be suppressed to reduce the sound pressure level loss. it can.

  In Embodiment 1, the cross-sectional shape of the convex bent portion 21a has been described as a V-shape. However, as shown in FIGS. 3, 4 and 5, the cross-sectional shape of the bent portion 21b is a U-shaped cross-section. The bent portion 21c having a rectangular shape and the bent portion 21d having an I-shaped cross-section may be configured, and even if these cross-sectional shapes are used, the same effect as the electromagnetic transducer 1 of the first embodiment can be obtained. it can.

Embodiment 2. FIG.
In the electromagnetic transducer 1 according to the first embodiment, the configuration in which the convex bending portion 21a is formed on one surface of the vibration film 20 has been described. However, in the second embodiment, the convex bending is formed on both surfaces of the vibration film 20. A configuration in which the portion 21a is formed will be described.
FIG. 6 is a cross-sectional view showing the configuration of the electromagnetic transducer 1 of the second embodiment.
In addition, about the same structure as FIGS. 1-5, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

  As shown in FIG. 6, the electromagnetic transducer 1 is supported so that the diaphragm 20 is sandwiched between the outer edges of the casing composed of the upper and lower frames 30, and is attached to the inner surfaces of the upper and lower frames 30 facing both surfaces of the diaphragm 20. The permanent magnet 10 is bonded and fixed.

  The permanent magnets 10 are arranged so that the polarities are alternately different as in the first embodiment, and have a predetermined gap as a gap, and convex bent portions 21 a are formed on both surfaces of the vibrating membrane 20. It is formed so as to be disposed in the gap 11 therebetween.

  As described above, in the electromagnetic transducer 1 according to the second embodiment, the coils 22 of the convex bent portions 21 a formed on both surfaces of the vibration film 20 are arranged in the gap 11 between the permanent magnets 10 of the upper and lower frames 30. Thus, the same effect as in the first embodiment can be obtained. Further, the diaphragm 20 can be protected by covering the diaphragm 20 so as to be sandwiched between the frames 30 from above and below.

  In the second embodiment, the bent portion 21a having a V-shaped cross-section is shown and described. However, similarly to the first embodiment, the bent portions 21b, 21c, and 21d having different cross-sectional shapes may be used. The effect of can be obtained.

  DESCRIPTION OF SYMBOLS 1 Electromagnetic transducer, 10 Permanent magnet, 11 Gap, 20 Vibration membrane, 21a, 21b, 21c, 21d Bending part, 22 Coil, 23 Edge, 30 frame, 31 Sound emission hole.

Claims (6)

Strip-shaped permanent magnets arranged so as to have a predetermined gap and alternately different polarities;
A convex bent portion is formed along a predetermined direction of the substrate, a coil is formed on the surface of the convex bent portion, and the convex bent portion is arranged in a gap between different polarities of the permanent magnet. Vibrating membrane,
An electromagnetic transducer comprising: a frame that houses the permanent magnet and supports the vibrating membrane.   The electromagnetic transducer according to claim 1, wherein a cross-section of the convex bent portion formed on the vibrating membrane is V-shaped.   The electromagnetic transducer according to claim 1, wherein a cross section of the convex bent portion formed on the vibration film is U-shaped.   The electromagnetic transducer according to claim 1, wherein a cross section of the convex bent portion formed on the vibration film is rectangular.   The electromagnetic transducer according to claim 1, wherein a cross section of the convex bent portion formed on the vibrating membrane is I-shaped.   The convex bending part of the said vibration film is formed in both surfaces of the said vibration film, The said permanent magnet is arrange | positioned at the both surfaces side of the said vibration film, Any one of the Claims 1-5 characterized by the above-mentioned. The electromagnetic transducer according to claim 1.

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